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Chapter 13
Our calculations agree with Baumgartner and Reichel in showing a
minimum in evaporation for the latitude band 25°-30°N, although the
magnitudes are different (we calculate 308 mm, while Baumgartner and
Reichel give 342 mm). Overall, our values are generally within the range of
previous estimates.
The zonal variations of fractional transpiration, interception and soil
evaporation are shown in Fig. 3. Transpiration is clearly the dominant
fraction over most of the land surface, except at high latitudes where soil
evaporation is the dominant fraction. Soil evaporation also appears as the
dominant fraction in the 25°-35°N latitude band, where deserts occupy
extensive areas (Sonaran, Chihuahuan, Sahara, Arabian, Iranian, and Thar
deserts). The transpiration component decreases, while the soil evaporation
component increases in the latitude band 20°-35°S, due to the deserts of
southern Africa and Australia. Increase in transpiration in the latitude band
35°-40°S is due to forested areas, pasture and croplands in South America,
Australia and New Zealand. South of 40°S, Patagonian desert appears as a